Respiration is the process through which the cells of our body produce the energy that is required for performing many important tasks. Each cell of our body utilizes the food we eat by respiration to break down the glucose present in the food into usable energy. The energy that is released during this process of respiration is used for different tasks, including the movement of our muscles, repair and growth of the cells, maintaining the temperature of our body, etc. The process of respiration has two main types. The first one is aerobic respiration while the other one is anaerobic respiration.

Aerobic Respiration Equation

Aerobic Respiration is the process in which the use of air or oxygen in particular is made for converting glucose in to energy. Since this process requires the inhalation of oxygen or air, it is referred to as aerobic which means anything involving the use of air. The aerobic respiration equation is:

Glucose + Oxygen ------------à Carbon dioxide + Water + Energy

The above equation clearly shows that in the process of aerobic respiration the glucose is broken down with the help of oxygen into energy accompanied by the formation of byproducts in the shape of water and carbon dioxide. The chemical version of this aerobic respiration equation is:

C₆H₁₂O₆ + 6O₂ -------------------à 6CO₂ + 6H₂O + 2900 kJ/mol

This equation also showcases the process of aerobic respiration and tells us that energy of about 2900 kJ is generated when a single mole of glucose comes in contact with oxygen. This extraordinary amount of energy is stored by the body in a special molecule that is known as Adenosine triphosphate or ATP for short. Labeled as an energy molecule, the ATP is where all the energy produced from aerobic respiration and is utilized whenever it is needed.

The process of aerobic respiration for both plants and animals is exactly the same and follows the exact equation mentioned above. However, the plants take in the oxygen through the stomata. Unlike animal cells that take in glucose as food from external sources, the plant cells have to make glucose for themselves through the process of photosynthesis and then convert this glucose into energy through respiration. The following is the equation for the process of photosynthesis taking place in the plant cells:

Carbon dioxide + Water + (Energy as Sunlight) ------------à Glucose + Oxygen

It is clear from this equation that the plants cells follow a total opposite road when producing their food through the process of photosynthesis than is taken by them during aerobic respiration. Plant cells carry out both these processes during the daytime when sunlight is available, with photosynthesis taking place much more rapidly than respiration. However, at night when there is no sunlight, the plant cells focus only on respiration.

Anaerobic Respiration Equation

As opposed to aerobic respiration, anaerobic respiration does not require the involvement of oxygen. The situation in which this process becomes necessary for the body is when the oxygen supply is low. With not enough oxygen available for conducting aerobic respiration, both plants and animal cells make use of anaerobic respiration to get the energy required by them for sustenance. In this process, oxygen is not used for the breakdown of glucose.

1. In Animals

The muscles present in our body require energy for working which is generated when they respire aerobically using the glucose and oxygen that are supplied to them through the blood. However, in some circumstances, the supply of oxygen to the muscle cells becomes insufficient. For instance, while performing a strenuous exercise, our muscles require consistent supply of oxygen to keep on respiring and generating energy, but the heart and lungs are unable to keep up this supply. In such a situation, the muscles start respiring anaerobically instead of waiting for the oxygen to be supplied to them. The equation for the process of anaerobic respiration is:

Glucose -------------à Lactic Acid + Energy

The equation clearly shows that the glucose is broken down without any use of oxygen to release energy and produce lactic acid as a by-product instead of carbon dioxide and water. The chemical equation for this process is:

C₆H₁₂O₆ -----------------à 2C_3­H₆O₃ + 120 kJ/mol

It is evident that this process is an efficient one which produces a far less amount of energy in comparison to aerobic respiration because of the partial breakdown of glucose. Furthermore, this inefficiency is accompanied by the production of lactic acid which is a very harmful chemical that can produce cramps in the muscle if its amount increases in the body. For the body to eliminate the buildup of lactic acid, it requires oxygen to break it down further. Oxygen debt is the name given to this quantity of oxygen needed by the body for getting rid of the poisonous lactic acid.

2. In Plants

Plants also face situations in which their oxygen supply gets diminished or runs out completely. This can happen if the soil in which the plant is present becomes waterlogged. In such circumstances, the plants make use of anaerobic respiration as well. The equation for this process is:

Glucose -----------------à Ethanol + Carbon dioxide + Energy

C₆H₁₂O₆ --------------à 2C₂H₅OH + 2CO₂ + Energy

The yeast cells are most likely to make use of anaerobic respiration which is given the name of fermentation as well and it is used for making bread and alcohol too.